Nasa can now forecast sinkholes

But probably couldn't have saved the Corvettes in Bowling Green, Kentucky.

Two years ago, a giant sinkhole swallowed trees whole in a Louisiana bayou. This year, Nasa says it could have predicted it.

It might sound like too little too late, but with five-to-ten times more sinkholes occurring in this country because of the wet weather this year, any potential tool for mapping precarious landmasses will be most welcome.

The sinkhole Nasa is basing its study on, near Bayou Corne, was a monster measuring 10.1 hectares. It was 229m (751ft) deep by the time it ceased swallowing everything in sight. In a paper published in the journal Geology, Cathleen Jones and Ron Blom, from the Jet Propulsion Laboratory, have shown how radar data captured by Nasa's Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) between 2011 and 2012 could have been used to predict the natural catastrophe.

The UAVSAR captures interferometric synthetic aperture radar (InSAR) data—the returning waves the aircraft captures are used to generate digital surface elevation and deformation maps. It's the same technique used to assess fault lines, or even glaciers, capturing incremental changes at the centimeter scale over the course of years.

Although it would seem impossible to predict sinkholes, which happen so suddenly (at least the cover-collapse kind), the groundwork that causes them is being laid over some time. They can occur when rainwater and all the acids it carries permeate the soil to reach soluble rockbeds that are vulnerable, often made from limestone, gypsum, or salts. Over time, chunks begin to erode to create holes and break the connections between the layers. Loose soil layers from above then fill those gaps to create an unstable replacement. Eventually, when these holes and gaps grow too great, this "cover" of soil will collapse. In the case of Bayou Corne, there was also an existing hole to contend with—an underground storage space 914m (2,998ft) below the surface connected to a well—and often sinkholes occur when a natural underground cave already exists.

Those loose soil particles trickling down to the earth below to fill the gaps before the collapse, however, could be a possible sign of danger. And this is essentially what the radar captured—incremental movements in soil particles that over time represent an indicative shift.

The data showed that the surface layer moved 26cm horizontally a month before the collapse, in the direction where the collapse was to occur. These movements were happening in a larger area, stretching around the sinkhole to 500m × 500m.

Although the sinkhole occurred in August 2012, data showed the deformation was still growing in October 2012 and could potentially start inching too close to another underground storage zone.

"While horizontal surface deformations had not previously been considered a signature of sinkholes, the new study shows they can precede sinkhole formation well in advance," said Jones. "This kind of movement may be more common than previously thought, particularly in areas with loose soil near the surface… At Bayou Corne, it appears that material is continuing to flow into the huge cavern that is undergoing collapse."

The authors conclude in Geology: "This work suggests that InSAR data collected operationally for hazard monitoring could, in some cases, identify sinkhole development before surface collapse and decrease subsequent danger to people and property."

It's a big "could," though. Plenty of other factors come into play with any sinkhole. The large salt dome that sits below the surface at the bayou was being used by companies to store gases and make salt water for local factories, and a class-action lawsuit has since been filed against two of those, Texas Brine and Occidental Chemical. For preventative measures, it might be better to keep a closer eye on manmade practices.

But still, the localized groundshift in the months prior to the collapse do present interesting possibilities for future monitoring. It seems to make sense to monitor regions where natural or manmade underground caves pose a threat.

Coauthor Blom admits: "Our discovery at Bayou Corne was really serendipitous. But it does demonstrate one of the expected benefits of an InSAR satellite that would image wide areas frequently."

Now, all of a sudden, I'm slightly jealous of all those rock nerds that studied geology ;-)

I have to wonder, if in theory, this could happen under the ocean somewhere... and kinda cascade down layer after layer after layer... enough that a noticeable drop in sea level could occur? Maybe that's where Mars' oceans went... ?

There are sink holes appearing all over the UK too, swallowing people's cars and cracking their houses and such. The scale is much smaller. I can't help but wonder if its related to the new technique of fracking where explosions are rigged up underground to release natural gasses upwards for collection. What exactly happens to the cavities and caverns deep underground after the gasses have gone... and water finds its way into them... could well be sink holes, if you ask me.

I hate to be "that guy" but the headline is bullshit. "Nasa can now forecast sinkholes!" Then when one reads the article, it's more like a hypothetical than an actual achievement.

Quote:

The authors conclude in Geology: "This work suggests that InSAR data collected operationally for hazard monitoring could, in some cases, identify sinkhole development before surface collapse and decrease subsequent danger to people and property."

It's a big "could," though. Plenty of other factors come into play with any sinkhole.

Seriously? I'd rather have Ars write up their own version than pull this from Wired, even if it means waiting until Monday.

There are sink holes appearing all over the UK too, swallowing people's cars and cracking their houses and such. The scale is much smaller. I can't help but wonder if its related to the new technique of fracking where explosions are rigged up underground to release natural gasses upwards for collection. What exactly happens to the cavities and caverns deep underground after the gasses have gone... and water finds its way into them... could well be sink holes, if you ask me.

It seems like fracking might be connected to some earthquakes, but it is probably far too deep to create sink holes. Fracking is usually done at incredible depths, 5000 to 20,000 feet deep, far, far deeper than sinkholes would be. I suspect 4000-19,000 feet of intervening rock is plenty to support the surface.

The author seems to assume i already know since it isn't explained or linked in the article.

Alas, the article doesn't explain that this method wouldn't have worked for finding sinkholes under buildings, since the presence of the building makes it impossible to see the movement of the ground under it.

I hate to be "that guy" but the headline is bullshit. "Nasa can now forecast sinkholes!" Then when one reads the article, it's more like a hypothetical than an actual achievement.

Quote:

The authors conclude in Geology: "This work suggests that InSAR data collected operationally for hazard monitoring could, in some cases, identify sinkhole development before surface collapse and decrease subsequent danger to people and property."

It's a big "could," though. Plenty of other factors come into play with any sinkhole.

Seriously? I'd rather have Ars write up their own version than pull this from Wired, even if it means waiting until Monday.

"Nasa can now predict sinkholes" is pretty damn close to "Data possessed by Nasa could, in some cases, be used to identify developing sinkholes before they collapse". Trimming away limiters and modifiers, and replacing precise phrases with commonly-understood broad terms is a standard journalistic practice. It's called simplifying or summarizing.

If you want precise, unambiguous journalism, you'll have to stick to the jargon-filled morasses of academic journals.

"Nasa can now predict sinkholes" is pretty damn close to "Data possessed by Nasa could, in some cases, be used to identify developing sinkholes before they collapse". Trimming away limiters and modifiers, and replacing precise phrases with commonly-understood broad terms is a standard journalistic practice. It's called simplifying or summarizing.

If you want precise, unambiguous journalism, you'll have to stick to the jargon-filled morasses of academic journals.

"The difference between the almost right word and the right word is really a large matter—’tis the difference between the lightning-bug and the lightning." -Mark Twain.

my understanding about the usage of underground salt domes/caverns for storing natural gas is that they're naturally occurring. texas brine (who my brother used to work for) provides brine water (basically water with the maximum amount of salt that will stay in suspension - smells horrid) to not only strengthen and repair these domes, but to also help displace the gas when it's pumped out for delivery to customers. i haven't heard of manmade salt domes before. so to me, people suing texas brine just sounds like a money grab.

The challenges with techniques like this are several fold:InSAR creates enormous amounts of data and is quite detailed. it's one thing to fly a plane with the SAR over a particular thing and spend a year working on the data from a few hour's data take. It's another to screen entire states or counties.

There's a false positive/false negative problem. What the original authors have done is say "hey, if you see this, in one instance it resulted in a sink hole". How do we know that if you UAVSARed the entire US you'd not get 100s of false alarms. Someday, we'll have the processing horsepower to do this, but not today.

Don't know about Texas, in California, city of San Francisco, the thickness requirement for a concrete foundation of a single family home dwelling structure to be 5" to 6" in thickness. So this is a doom on a solid ground with no second story above. It still looks awful thin but the water could have taken away part of the concrete out from underneath during the period of many years. The sink hole didn't happen in one day.

Two years ago, a giant sinkhole swallowed trees whole in a Louisiana bayou. This year, Nasa says it could have predicted it.

I'll go one better. I can predict it within an hour after it happens - no need to wait a full year afterwards!

Jokes aside, this is a potentially useful observation. I think the trick will be catching sight of the signs of impending collapse within the sea of raw data in a timely manner.

Your comment is correct even though you phrased it as a joke. The sinkhole could be "predicted" from measurements of ground movement only because they knew where and when it would occur. The original paper acknowledges this, but the Ars write up (especially the headline) is misleading.